Polishing film

ABSTRACT

The present invention provides a polishing film with which, even when water containing impurity ions is used as a polishing liquid, the abrasive particles comprising SiO 2  are less apt to adhere to the polished surface, e.g., the polished surface of an end of an optical fiber itself, and which is less apt to cause the optical loss attributable to scratches or edge chips in the polished surface. The polishing film hence renders good finish-polishing quality possible. This polishing film is characterized by comprising a substrate and an abrasive layer which has been disposed on a surface of the substrate and which comprises abrasive particles comprising SiO 2 , a binder resin, and an adhesion inhibitor containing a phosphorus compound.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Section 371 of International Application No. PCT/JP2012/002703, filed Apr. 18, 2012, which was published in the Japanese language on Nov. 1, 2012, under International Publication No. WO 2012/147312 A1 and the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a polishing film. In further detail, the present invention relates to a polishing film used for polishing a polishing surface of a substance to be polished (such as an optical fiber, an optical lens or a magnetic disc substrate).

Conventionally, as a connecting member of optical fibers in an optical fiber communication network, an easily-detachable optical fiber connector is widely used. When the optical fibers are connected using the optical fiber connector, they are connected in a situation where respective connecting end surfaces {end surfaces of an optical fiber body (glass fiber) and end surfaces of, for example, ferrule made of zirconia coating the optical fiber body} directly come face-to-face with each other.

Consequently, from a viewpoint to sufficiently reduce a light loss (communication loss) of the optical fiber after being connected, it is important to precisely polish the connecting end surfaces of the optical fiber connector to be connected (the end surface of the optical fiber body and the end surface of ferrule) so as to be a smooth surface where scratch and/or a chipped portion(s) (for example, a defect, such as an edge portion of the polished surface) have been sufficiently diminished.

Such polishing of the connecting end surface of the optical fiber connector is performed in a plurality of processes: a roughly-finishing polishing process, a semi-finishing polishing process and a final-finishing polishing process, and among them, in the final-finishing polishing process, a polishing material is secured by adhering to an elastic body pad on a polishing surface plate, and polishing processing is performed by rotating and sliding the polishing surface plate while the connecting end surface of the optical fiber connector is pressed onto the surface of the polishing material on contact with a polishing liquid, such as water.

As the polishing material used for this final-finishing polishing process, for example, in Patent Literature 1 to Patent Literature 3, a polishing film (or abrasive tape) having an abrasive layer containing at least abrasive particles and a binder resin, and, a substrate supporting the abrasive layer is proposed.

-   Patent Literature 1: Japanese Patent Laid-Open Application     H08-336758 -   Patent Literature 2: Japanese Patent Laid-Open Application     2002-239924 -   Patent Literature 3: Japanese Patent Laid-Open Application     2007-190613

BRIEF SUMMARY OF THE INVENTION

However, from the viewpoint to obtain sufficient polishing precision, while sufficient prevention from scratching the connecting end surface by at least either one of polishing debris that is generated when a connecting end surface of the optical fiber connector is polished using a polishing film or abrasive particles that are dislodged from the abrasive layer and from leaving these polishing debris or abrasive particles on the connecting end surface even after the polishing treatment, there is still room for improvement with the polishing films proposed in Patent Literature 1 to Patent Literature 3.

In other words, with the conventional polishing films, for example, in the final-finishing polishing process of the connecting end surface of the optical connector, when abrasive particles containing SiO₂ are used, because the optical fiber body in the optical fiber connector contains SiO₂, abrasive particles containing SiO₂ may become adhered to the optical fiber connector, and if there is such adherence, it causes scratching and/or chipping (for example, a defect of an edge portion on the polishing surface and the like), and a light loss could occur on the connecting end surface of the optical fibers after being connected.

Particularly, recently, from the viewpoint of cost reduction in the polishing process, not ultrapure water or purified water but filtered water, which can be obtained without ion exchange and distilling but only by filtering for the purpose of foreign body removal, is used as a polishing liquid, and if such filtered water is used, because of an effect of impurity ions in the filtered water, abrasive particles containing SiO₂ dislodged from the abrasive layer are agglutinated and their dispersibility is inhibited, and an amount of adherence of the abrasive particles including SiO₂ onto the end surface of the optical fiber body after polishing may be increased. It is difficult for the adhered abrasive particles to be removed, and it causes scratching and chipping (for example, a defect of the edge part on the polishing surface and the like), and there is a problem where a light loss could occur on the connecting end surface of the optical fibers after being connected.

Then, the objective of the present invention is to provide a polishing film that can realize excellent polishing finished quality that is not likely to cause adherence of abrasive particles containing SiO₂ onto the polishing surface, such as an end surface of the optical fiber after being polished, and that is not likely to undergo a light loss caused by scratching and/or chipping (for example, a defect at the edge portion on the polishing surface and the like) on the polishing surface.

As described above, when abrasive particles containing SiO₂ are used and water containing impurity ions is used as polishing liquid, abrasive particles containing SiO₂ are easily attached onto a polishing surface of a substance to be polished, such as an end surface of the optical fiber body after being polished, and if such adherence occurs, it is common sense for conventional persons skilled in the art that it could cause scratching and/or chipping (for example, a defect at an edge portion on the polishing surface and the like) on the polishing surface.

In the meantime, the inventors of the present application, as a result of more keen study in order to accomplish the objective, regardless of the common recognition for the persons skills in the art, discovered that adherence of abrasive particles containing SiO₂ onto a polishing surface of a substance to be polished, such as an end surface of an optical fiber body after being polished, as long as an anti-adhesive agent containing a phosphorus compound in an abrasive layer is used, even though abrasive particles containing SiO₂ are used for the abrasive layer and water containing impurity ions is used as a polishing liquid, and they accomplished the present invention.

In other words, the present invention relates to a polishing film, at least having: a substrate, and an abrasive layer that is arranged on a surface of the substrate, and that has abrasive particles containing SiO₂, a binder resin, and an anti-adhesive agent containing a phosphorus compound.

As described above, the polishing sheet of the present invention has a configuration having an anti-adhesive agent containing a phosphorus compound in an abrasive layer. Since this phosphorus compound has a chelate formative ability, even if water containing impurity ions is used as a polishing liquid, because the impurity ions are adsorbed due to the chelate formation with the impurity ions, agglomeration of abrasive particles containing SiO₂ that have been dislodged from the abrasive layer due to the effect of the impurity ions and adherence of the abrasive particles onto the polishing surface of the substance to be polished can be inhibited. In other words, because of the anti-adhesive agent containing a phosphorus compound, dispersibility of dislodged abrasive particles containing SiO₂ is improved, and agglomeration of the abrasive particles and easiness to be adhered onto the polishing surface can be effectively inhibited.

Further, in the polishing film of the present invention, it is preferable that the phosphorus compound is a compound having a phosphate group and/or a phosphonate group.

If the polishing film of the present invention having such configuration is used, because of a phosphate group and/or a phosphonate group, the phosphorus compound and the impurity ions facilitate the formation of chelate; therefore, dispersibility of dislodged abrasive particles containing SiO₂ is more certainly improved, and agglomeration of the abrasive particles and easiness to be adhered onto the polishing surface can be more certainly inhibited.

Further, it is preferable that the polishing film of the present invention is for a substance to be polished containing SiO₂.

As the substance to be polished containing SiO₂, for example, optical fibers, optical fiber connectors, optical lenses, magnetic disc substrates and the like are exemplified.

According to such configuration, the abrasive particles containing SiO₂ can be dislodged from both the abrasive layer and the substance to be polished, but since the dispersibility of the dislodged abrasive particles containing SiO₂ is also improved and the agglomeration of the abrasive particles and easiness to be adhered onto the polishing surface can be effectively inhibited, the effect of the present invention can be benefited.

In other words, in the final-finishing polishing process of the connecting end surface of the optical fiber connector, when the polishing film of the present invention and water containing impurity ions are used, even though the optical fiber body in the optical fiber connector contains SiO₂, the abrasive particles containing SiO₂ are not likely to agglomerate and adhered on the end surface (polishing surface) of the optical fiber body after being polished, and generation of scratching and/or chipping (for example, a defect at an edge portion on the polishing surface and the like) and a light loss on the connecting end surface of the optical fibers after being connected can be effectively inhibited.

According to the present invention, even when water containing impurity ions is used as a polishing liquid, the abrasive particles containing SiO₂ are not likely to be adhered onto the polishing surface of the substance to be polished, and a polishing film that can realize excellent polishing finished quality that is not likely to cause a light loss attributable to scratching or (defective) chipping on the polishing surface can be obtained.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.

In the drawings:

FIG. 1 is a schematic longitudinal sectional view of one embodiment of the polishing film of the present invention.

FIG. 2 is a picture of a polishing surface of an optical fiber connector imaged in Example 1 of the present invention (400×).

FIG. 3 is a picture of a polishing surface of an optical fiber connector imaged in Comparative Example 1 of the present invention (400×).

DETAILED DESCRIPTION OF THE INVENTION

Hereafter, preferred embodiments of the polishing film of the present invention are described in detail with reference to drawings. Furthermore, in the description below, the same or equivalent portions/parts are marked with the same symbols, respectively, and redundant descriptions may be omitted, and drawings are for conceptually explaining the present invention; therefore, dimensions of each of illustrated constituents and their ratios may be different from actual ones.

FIG. 1 is a pattern cross-sectional view showing the basic configuration of one embodiment of the polishing film of the present invention. A polishing film 1 of the present embodiment shown in FIG. 1 is configured by mainly having a substrate 2, and an abrasive layer 3 that is arranged on one surface of the substrate 2, and that has abrasive particles 3 a containing SiO_(2, binder resin 3) b and an anti-adhesive agent 3 c containing a phosphorus compound. Furthermore, as mentioned above, FIG. 1 conceptually shows the structure of the polishing film 1 of the present invention, and in actuality, a ratio of the abrasive particles 3 a is overwhelmingly high, and the anti-adhesive agent 3 c may be dissolved and may be adhered to the abrasive particles 3 a or independently existing within the binder resin 3 b.

The substrate 2 is a member for supporting and securing the abrasive layer 3. The substrate 2 shown in FIG. 1 presents a film-state or sheet-state configuration having a first principal surface S1 and a second principal surface S2 facing with each other nearly in parallel. Then, the abrasive layer 3 is arranged on the first principal surface S1 of the substrate 2.

As such substrate 2, as long as materials have moderate rigidity and support the abrasive layer 3 and excellent adhesiveness/adhesive properties with the abrasive layer 3 can be secured on the occasion of polishing process of a substrate to be polished, such as an optical fiber connector; the materials are not particularly limited, and any known substrate of the polishing film can be used.

As the constitutional material of the substrate 2, any known thermoplastic resins are preferably usable, and for example, acrylic resin, polycarbonate, polyethylene terephthalate (PET), polypropylene or polyethylene and the like is preferably usable. Further, a biaxially-oriented film, such as polyethylene terephthalate (PET) or polyethylene, is also usable.

For thickness of the substrate 2, appropriate thickness should be arbitrarily set according to a use application of the polishing film 1. For example, when the polishing film 1 is used for polishing treatment of the connection end surface of the optical fiber connector, from a viewpoint of convenience (handling easiness), it is preferable that the thickness of the substrate 2 is 30 μm to 150 μm.

Further, it is not shown in FIG. 1, but surface treatment, such as corona treatment or primer treatment, may be applied onto the first principal surface S1.

If the corona treatment is applied, the first principal surface S1 of the substrate 2 is finely roughened and its surface area can be increased, and adhesiveness/adhesive properties between the first principal surface S1 and the abrasive layer 3 can be improved with an anchor effect, as well.

Further, the constitutional materials of the primary treated layer that is formed by the primer treatment are not particularly limited as long as adhesiveness/adhesive properties between the substrate 2 and the abrasive layer 3 can be secured, and for example, water-soluble or water-dispersible polyester resin or acrylic resin (for example, see Japanese Patent Publication 554-43017), and for example, resin where an unsaturated bond-containing compound is grafted to a water-soluble or water-dispersible hydrophilic group-containing polyester resin (for example, see Japanese Laid-Open Patent Application H2-310048) are preferably usable.

For thickness of the primer treated layer, appropriate thickness should be arbitrarily set according to a use application of the polishing film 1. For example, when the polishing film 1 is used for polishing treatment of the connection end surface of the optical fiber connector, from a viewpoint of the convenience (handling easiness), it is preferable that the thickness of the primer treated layer is 0.3 μm to 0.8 μm.

The abrasive layer 3 is a layer established for polishing a substance to be polished. The abrasive layer 3 has a configuration having the abrasive particles 3 a containing SiO₂, the binder resin 3 b and the anti-adhesive agent 3 c containing a phosphorus compound.

The abrasive layer 3, from a viewpoint to certainly obtain the effect of the present invention (to improve dispersibility of the abrasive particles 3 a containing dislodged SiO₂, and to prevent from agglomeration of the abrasive particles 3 a and adherence onto the polishing surface) mentioned above, has characteristics in points to form chelate with impurity ions in a polishing liquid, which causes the agglomeration of the abrasive particles 3 a and adherence onto the polishing surface, and to contain the anti-adhesive agent 3 c that prevents the adherence of the abrasive particles 3 a onto the polishing surface.

As shown in FIG. 1, the abrasive layer 3 presents a layer configuration having certain thickness in the case of viewing from the cross-sectional direction (in other words, viewing the longitudinal cross-section in the nearly normal direction of the first principal surface S1 and the second principal S2 from the direction that is nearly parallel to the first principal surface S1 and the second principal surface S2).

Furthermore, a continuous or discontinuous groove may be established on the surface of the abrasive layer 3. Further, the abrasive layer 3 may be divided into a plurality of portions. For example, in the case of viewing from the nearly normal direction of the first principal surface S1 and the second principal surface S2 of a substrate 10, the abrasive layer 3 may be an abrasive layer having a configuration where two or more abrasive structures having a surface presenting nearly rectangular shape or nearly hexagonal shape are arranged in parallel across a groove, respectively. At this time, the groove formed between the two or more abrasive structures is formed to be continuous or discontinuous throughout the entire region of the abrasive layer, and the bottom portion of the groove may be formed so as to achieve surface of the substrate.

The abrasive particles 3 a are members for polishing a substance to be polished, and for the abrasive particles containing SiO₂, for example, conventionally-known ones, such as colloidal silica (including organo silica sol where colloidal silica is dispersed into an organic solvent), dry silica, wet silica or molten silica, are variously usable.

Further, the abrasive particles 3 a, from a viewpoint not to contain coarse particles causing scratching and defects on the polishing surface, should have 0.001 μm to 1 μm of particle size, and in addition, from viewpoints not to increase grinding efficiency if the particle size is too small, and to decrease the number of particles acting on polishing and to reduce the grinding efficiency if the particle size is too large, it is preferable to have 0.01 μm to 0.2 μm of particle size. The particle size herein is a median size of the particle size distribution using dynamic light scattering, and for example, this can be implemented using a dynamic light scattering type particle size distribution measuring instrument manufactured by HORIBA, Ltd.

The binder resin 3 b is a material contained in the abrasive layer 3 in order to maintain the abrasive particles 3 a and the anti-adhesive agent 3 c in the situation of being dispersed within the abrasive layer 3, and to support/secure the abrasive layer 3 itself in the situation of being cohered onto the second principal surface S1 of the substrate 2.

The binder resin 3 b is not particularly limited as long as excellent dispersibility of the abrasive particles 3 a and the anti-adhesive agent 3 c and excellent adhesiveness/adhesive properties to the substrate (to the primer treated layer in the case of establishing the primer treated layer) can be secured, and ones that are used as a binder resin in the abrasive layer of the conventionally-known polishing film are usable.

As the binder resin 3 b, for example, polyurethane resin, phenol resin, epoxy resin, polyester resin, cellulose resin, ethylene copolymer, rubber-base resin, polyvinyl acetal resin, polyacrylic resin, polyvinyl alcohol resin, polyvinyl chloride resin, polyvinyl acetate resin, polyamide-base resin, aminoplast-base resin and phenoxy resin are exemplified. Further, for the binder resin 3 b, at least a portion may be cross-linked.

Further, additives, such as a cross-linking agent (details will be described later) including isocyanate resin, a coupling agent, a lubricant agent and the like may be contained in the abrasive layer 3 according to a type of the binder resin 3 b to the extent of not impairing the effect of the present invention.

For the phosphorus compound constituting the anti-adhesive agent 3 c, various agents are usable as long as chelate is formed with impurity ions contained in water, which is used as a polishing liquid, and the impurity ions are acquired.

As such phosphorus compound, as long as chelate can be formed with impurity ions contained water (for example, calcium ion, sodium ion, magnesium ion, potassium ion and chloride ion), both an inorganic phosphoric compound and an organic phosphorus compound can be used, and from a viewpoint to enable to certainly form the chelate with the impurity ions, it is preferable to use ones having a phosphate group and/or a phosphonate group.

As the inorganic phosphorus compound, for example, phosphoric acid, phosphate, polyphosphoric acid, polyphosphate and the like are exemplified. As the polyphosphate, for example, a polymerized inorganic phosphoric acid-base compound that has two or more phosphorus atoms, and where alkali metal or alkali earth metal and the phosphorus atoms are bound together, such as sodium hexametaphosphate, is exemplified. As specific examples of polyphosphate, for example, tetrasodium pyrophosphate, disodium pyrophosphate, sodium tripolyphosphate, sodium tetrapolyphosphate, sodium heptapolyphosphate, sodium decapolyphosphate, sodium metaphosphate, sodium hexametaphosphate, their potassium salts and the like are exemplified. Among these, one or more can be used.

As the organic phosphorus compound, phosphonic acid and its derivatives are exemplified as preferable ones, and for example, phosphonoacetic acid or its salt; 2-phosphonobutane tricarboxylic acid or its salt; iminodialkylphosphonic acid, such as imino dimethylphosphonic acid, or its salt; alkyl diphosphonic acid or its salt; ethylenediaminetetra (methylenephosphonic acid) or its salt; diethylenetriaminepenta (methylenephosphonic acid) or its salt; aminotri (methylenephosphonic acid) or its salt; and hydroxyalkylidene bisphosphonic acid, such as 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), or its salt can be exemplified. Among these, one or more can be used.

Contents of the abrasive particles 3 a containing SiO₂ and the binder resin 3 b in the abrasive layer 3 are different according to an equivalent of a phosphate group and/or a phosphonate group in the phosphorus compound, but these should be arbitrarily adjusted to the extent of not impairing the effect of the present invention.

A lower limit value of the content of the phosphorus compound constituting the anti-adhesive agent 3 c in the abrasive layer 3, for example, should be 0.1% by mass of the abrasive layer 3, but in order to further certainly obtain the effect of the present invention, 1% by mass is preferable. Further, an upper limit value of the content of the anti-adhesive agent 3 c containing a phosphorus compound in the abrasive layer 3 should be arbitrarily selected to the extent of not impairing the polishing effect of the abrasive layer 3 and adhesiveness/adhesive properties to the substrate 2. The content of the phosphorus compound constituting the anti-adhesive agent 3 should be 0.1% to 11% by mass, but it is preferably 1% to 7% by mass.

As described above, since the polishing film 1 of the present embodiment has the configuration having the anti-adhesive agent 3 c containing the phosphorus compound in the abrasive layer 3, even if water containing impurity ions is used as a polishing liquid, because the anti-adhesive agent 3 c adsorbs the impurity ions due to the chelate formation with the impurity ions, the abrasive particles 3 a dislodged from the abrasive layer 3 can be inhibited from agglomeration and adhering onto a polishing surface of the substance to be polished due to the effect of impurity ions.

Next, one example of a manufacturing method for the polishing film of the present embodiment is explained. The manufacturing method for the polishing film 1 of the present embodiment is, mainly, composed with a process to form the abrasive layer 3 on the first principal surface S1 of the substrate 2.

(a) Preceding Process (Optional)

When primer treatment as mentioned above is applied onto the first principal surface S1 of the substrate 2 as the preceding process, for example, a primer treated layer is formed by a conventionally-known method, such as a method of drying after a primer agent is sprayed onto the principal surface S1 of the substrate 2 for coating. Further, a marketed product where a primer treated layer is pre-established on the first principal surface S1 of the substrate 2 may be used.

(b) Abrasive Layer Formation Process

As a method for forming the abrasive layer 3 on the principal surface S1 of the substrate 2 (on the primer treated layer in the case of establishing the primer treated layer), a known thin film manufacturing technology to the extent that adhesiveness/adhesive properties between the principal surface S1 of the substrate 2 (the primer treated layer in the case of establishing the primer treated layer) and the abrasive layer 3 can be adopted.

For example, the abrasive particles 3 a, the binder resin 3 b, the anti-adhesive agent 3 c, a solvent, a cross-linking agent and a dispersant (and other additive(s)) are mixed, and an application liquid where the abrasive particles 3 a are dispersed is prepared, and this application liquid is applied onto the first principal surface S1 of the substrate 2 (the primer treated layer in the case of establishing the primer treated layer). Next, the abrasive layer 3 can be formed by removing the solvent with drying of applied film obtained by the application.

Herein, the technique to apply the application liquid onto the first principal surface S1 of the substrate 2 (onto the primer treated layer in the case of establishing the primer treated layer) is not particularly limited, but any known coating method, such as bar coating, comma coating, spray coating, reverse roll coating, knife coating, screen printing, gravure coating or die coating, can be adopted.

Furthermore, the cross-linking agent is for cross-linking polymer molecules constituting the binder resin 3 b, and for forming a configuration where it is incorporated into the binder resin 3 b after cross-linkage. As this cross-linking agent, due to its high reactivity, from a viewpoint where the hard abrasive layer 3, which is difficult to be deformed during the polishing work, can be obtained, except for carbon in an NCO group, aromatic polyisocyanate with 6 to 20 of carbon number, aliphatic polyisocyanate with 2 to 18 of carbon number, alicyclic polyisocyanate with 4 to 15 of carbon number and aromatic-aliphatic polyisocyanate with 8 to 15 of carbon number are preferably exemplified.

Further, from the similar viewpoint above, as the cross-linking agent, modified substances of polyisocyanate (such as modified substances containing at least one type of organic group selected from a group constituting a urethane group, a carbodiimide group, an allophanate group, a urea group, a burette group, an uretodione group, an uretoimine group, an isocyanurate group and an oxazolidone group), and the polyisocyanate compounds above are also preferably exemplified. Further, a mixture formed by selecting two types or more from polyisocyanate, modified substances of polyisocyanate and polyisocyanate compounds above and may be used.

The solvent is not particularly limited as long as the binder resin 3 b is soluble. Specifically, for example, methyl ethyl ketone (MEK), isophorone, terpineol, N methylpyrrolidone, cyclohexanone, propylene carbonate, toluene, tetrahydrofuran (THF), ethyl acetate, N,N-dimethylformamide (DMF), 2-propanol and the like can be used.

Further, the dispersing agent is not particularly limited along as it is soluble in a solvent to be used, and the abrasive particles 3 a and the anti-adhesive agent 3 c can be dispersed in the binder resin 3 b. Specifically, polycarboxylate of long-chain polyaminoamide, alkylol amano amide, modified acrylic block copolymerization, unsaturated polycarboxylic polymer, sorbitan fatty acid ester, oleyl phosphate, and dodecyl sodium sulfate are usable. Furthermore, when the abrasive particles 3 a and the anti-adhesive agent 3 c can be dispersed in the binder resin 3 b in the application liquid without using any dispersant, any dispersant does not have to be used.

Furthermore, in order to form a groove in the abrasive layer 3 as mentioned above, a mask having configuration corresponding to the shape of the groove is arranged on the first principal surface S1 of the substrate 2 (on the primer treated layer in the case of establishing the primer treated layer), and the application liquid should be applied over that surface using, for example, bar coating, spray coating, screen printing or gravure coating. Other than that, a method for forming a groove by etching after the abrasive layer 3 is formed is also usable.

Thus, although one preferred embodiment of the present invention was explained, the present invention shall not be limited to that embodiment. The embodiment shown here is merely one example, and the designs are variously modifiable within the scope of technical concept and instruction; therefore, other embodiments can variously exist, and needless to say, they will belong to the technical scope of the present invention.

Hereafter, the polishing film of the present invention will be described in further detail with reference to examples and comparative examples, but the present invention shall not be limited to these examples.

EXAMPLE 1

An application liquid was prepared by mixing 66 parts by weight of organo silica sol (MEK-ST manufactured by Nissan Chemical Industries, Ltd., solid content: 30% by mass) as abrasive particles containing SiO₂; 3.9 parts by weight of acrylic resin (Acrynal #22-36 manufactured by Toei Kasei Co., Ltd., solid content: 29.6% by mass) as a binder resin; 0.5 parts by weight of isocyanate (Sumidule L75 manufactured by Sumika Bayer Urethane Co., Ltd., solid content: 75% by mass) as a cross-linking agent; and 0.3 parts by weight of phosphoric acid (solid content: 85% by mass) as an anti-adhesive agent into a mixed solvent of 25.3 parts by weight of methyl ethyl ketone, 3.8 parts by weight of 2-propanol and 0.2 parts by weight of purified water (manufactured by TRUSCO Nakayama Corporation).

The application liquid was applied onto one surface of a polyester film (Lumirror T91N manufactured by Toray Industries, Inc., thickness: 75 μm) as a substrate, using a bar coating method, and the polishing film 1 having an abrasive layer with 3 μm of thickness was obtained by drying at 100 ° C. with an oven. Proportion (% by mass) of each component in the application liquid was shown in Table 2, and the proportion of each component (solid content) in the abrasive layer was obtained from this proportion and solid content proportion and shown in Table 2.

[Evaluation Test]

The polishing film 1 obtained above was punched out to a rectangular shape with 114 mm×140 mm, and it was adhered to an elastic pad of a polishing machine (ATP-2100 manufactured by NTT Advanced Technology Corporation) and secured, and final finishing polishing to a connected end surface of an optical fiber connected (SC ferrule manufactured by SEIKOH GIKEN Co., Ltd.) after semi-finishing polishing, using water obtained only via filtration without ion exchange and distillation as a polishing liquid, was conducted for 120 seconds.

Furthermore, the semi-finishing polishing was conducted under conditions where a 1 μm polishing film with diamond abrasive grains (TOPX D105 manufactured by Bando Chemical Industries, Ltd.) was adhered and secured to an elastic pad of a polishing device (ATP-2100 manufactured by NTT Advanced Technology Corporation), and purified water (manufactured by TRUSCO Nakayama Corporation) was used as a polishing liquid and polishing was conducted for 120 seconds. Further, as the water (polishing liquid) obtained only via filtration without ion exchange and distillation, water that was prepared by removing debris from industrial water (Kobe City) with a mesh (#400) made of stainless steel (SUS) was used (without distillation and ion exchange). An electric conductivity of this polishing liquid was measured with an electric conductivity analyzer CM-20S manufactured by DKK-TOA Corporation, and it was 0.15 mS/cm (furthermore, the polishing liquid above contained impurity ions shown in Table 1 below. Detailed measurement method and measurement results of the impurity ions are shown in Table 1).

TABLE 1 Meter Shimadzu Ion Chromatograph Prominence (manufactured by Shimadzu Corporation) Measurement Anion Column: Shim-pack IC-SA1 conditions Mobile phase: 12 mM sodium hydrogen carbonate/0.6 mM sodium carbonate Flow rate: 1.0 mL/min Temperature: 30° C. Detector: Electric Conductivity Detector (CDD-10 Asp) Suppressor Injection volume: 25 μL Cation Column: Shim-pack IC-C3 Mobile phase: 2.5 mM oxalic acid Flow rate: 1.2 mL/min Temperature: 40° C. Detector: Electric Conductivity Detector (CDD-10 A) Nonpressor Injection volume: 25 μL Measurement Anion F  0.0860 mg/L results Cl 14.7540 mg/L Br  0.0500 mg/L NO₃  3.6100 mg/L SO₄ 19.4520 mg/L NO₂, PO₄ detection lower limit or less Cation Na  14.564 mg/L K  1.862 mg/L Mg  2.340 mg/L Ca  14.030 mg/L Li, NH₄ detection lower limit or less

A polished surface of the optical fiber connector after the final finishing polishing was observed with Video Fiber Microscope manufactured by WESTOVER (48 terminals), and a picture was taken (400×, shown in FIG. 2). When any extraneous matter and scratch(s) were not observed, it was rated as “excellent”, and when extraneous matter and scratch(s) were observed, it was rated as “defective”. Such evaluation test with 24 terminal/time was repeated twice, and results were shown in Table 2 with efficiency percentage indicated with {(number of “excellent” cases)/48}×100 (%).

EXAMPLES 2 TO 4 AND COMPARATIVE EXAMPLE 1

Polishing films 2 to 4 and a comparative polishing film 1 were produced as similar to Example 1 above except for changing the proportion of each constituent into the value shown in Table 2, and the evaluation test was conducted. Results were shown in Table 2. Further, for the comparative polishing film 1, a picture (400×) taken in the evaluation was shown in FIG. 3.

TABLE 2 Com- Comparative pound Example 1 Example 2 Example 3 Example 4 Example 1 name Proportion Proportion Proportion Proportion Proportion Proportion Proportion Proportion Proportion Proportion (solid in in in in in in in in in in content application polishing application polishing application polishing application polishing application polishing ratio (% liquid (parts liquid (% liquid (parts liquid (% liquid (parts liquid (% liquid (parts liquid (% liquid (parts liquid (% by by mass)) by mass) by mass) by mass) by mass) by mass) by mass) by mass) by mass) by mass) mass) 1 Organo 66.0 91.7 68.0 92.5 53.1 86.3 47.6 83.4 69.0 92.9 silica sol (30) 2 Acrylic 3.9 5.3 4.0 5.4 3.2 5.1 2.8 4.8 4.1 5.4 resin (29.6) 3 Methyl 25.3 0 26.0 0 20.3 0 18.2 0 18.2 0 ethyl ketone (0) 4 Isocyanate 0.5 1.7 0.5 1.7 0.4 1.6 0.3 1.3 0.3 1.7 (75) 5 Phos- 0.3 1.2 0.1 0.4 1.5 6.9 2.1 10.4 2.1 0 phoric acid (85) 6 2-propanol 3.8 0 1.3 0 20.5 0 27.6 0 27.6 0 (0) 7 Purified 0.2 0 0.1 0 1.0 0 1.4 0 1.4 0 water (0) Evaluation 94 75 92 73 27 results: efficiency percentage (%)  “Proportion in abrasive layer (% by mass)” indicates a rate of solid content.

EXAMPLE 5

A polishing film 5 was produced as similar to Example 1 except for using phosphonoacetic acid (manufactured by Wako Pure Chemical Industries, Ltd.) instead of phosphoric acid as an anti-adhesive agent, and the evaluation test was conducted. Results were shown in Table 3.

TABLE 3 Example 5 Proportion in Compound name application Proportion in (solid content proportion liquid (parts by polishing liquid (% by mass)) mass) (% by mass) 1 Organo silica sol (30) 66.0 91.5 2 Acrylic resin (29.6) 3.9 5.3 3 Methyl ethyl ketone (0) 25.3 0 4 Isocyanate (75) 0.5 1.7 5 phosphonoacetic acid (100) 0.3 1.4 6 2-propanol (0) 3.8 0 7 Purified water (0) 0.2 0 Evaluation results: 94 efficiency percentage (%)

EXAMPLE 6

A polishing film 6 was produced as similar to Example 1 except for using cellulose resin (Ethocel 100 manufactured by Nisshin & Co., Ltd.) instead of acrylic resin, and the evaluation test was conducted. Results were shown in Table 4.

TABLE 4 Example 5 Proportion in Compound name application Proportion in (solid content proportion liquid (parts by polishing liquid (% by mass)) mass) (% by mass) 1 Organo silica sol (30) 66.0 92.0 2 Cellulose resin (100) 1.1 5.1 3 Methyl ethyl ketone (0) 28.1 0 4 Isocyanate (75) 0.5 1.7 5 Phosphoric acid (85) 0.3 1.2 6 2-propanol (0) 3.8 0 7 Purified water (0) 0.2 0 Evaluation results: 90 efficiency percentage (%)

As it is clear from the results shown in Tables 2 to 4, if the polishing film of the present invention is used, it is difficult for abrasive particles containing SiO₂ to be adhered onto a polishing surface, such as an end surface of the optical fiber body after polishing, even when water containing impurity ions is used as a polishing liquid, and excellent polishing finishing quality where a light loss attributable to scratching or defect (chipping) is unlikely to occur on the polished surface can be realized.

The polishing film of the present invention can be preferably used for polishing of a polishing surface of a substance to be polished, such as an optical fiber, an optical lens or a magnetic disk substrate.

It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims. 

1. A polishing film at least comprising: a substrate, and an abrasive layer that is arranged on a surface of the substrate, and that has abrasive particles containing SiO₂, a binder resin, and an anti-adhesive agent containing a phosphorus compound.
 2. The polishing film according to claim 1, wherein the phosphorus compound is a compound comprising a phosphate group and/or a phosphonate group.
 3. The polishing film according to claim 1, for a substrate to be polished containing SiO₂.
 4. The polishing film according to claim 2, for a substrate to be polished containing SiO₂. 